[moderation] [perf?] KCSAN: data-race in __perf_event_read_value / event_sched_out (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8fdb05de0e2d Merge tag 'net-6.19-rc9' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15493a5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e27f4588a0f2183
dashboard link: https://syzkaller.appspot.com/bug?extid=3eba56c406a6345e4c08
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ac...@kernel.org adrian...@intel.com alexander...@linux.intel.com iro...@google.com james...@linaro.org jo...@kernel.org linux-...@vger.kernel.org linux-pe...@vger.kernel.org mark.r...@arm.com mi...@redhat.com namh...@kernel.org pet...@infradead.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ec4849f6af8e/disk-8fdb05de.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/79c8d2fd2b94/vmlinux-8fdb05de.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ddd0f3e3e081/bzImage-8fdb05de.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3eba56...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __perf_event_read_value / event_sched_out

write to 0xffff888154b55288 of 8 bytes by task 5751 on cpu 1:
__perf_update_times kernel/events/core.c:-1 [inline]
perf_event_update_time kernel/events/core.c:735 [inline]
perf_event_set_state kernel/events/core.c:754 [inline]
event_sched_out+0x47e/0x8f0 kernel/events/core.c:2391
group_sched_out kernel/events/core.c:2415 [inline]
__pmu_ctx_sched_out+0x3e7/0x530 kernel/events/core.c:3458
ctx_sched_out+0x273/0x2d0 kernel/events/core.c:3539
task_ctx_sched_out+0x4d/0x70 kernel/events/core.c:2859
perf_event_context_sched_out kernel/events/core.c:3746 [inline]
__perf_event_task_sched_out+0x474/0x710 kernel/events/core.c:3846
perf_event_task_sched_out include/linux/perf_event.h:1654 [inline]
prepare_task_switch kernel/sched/core.c:5049 [inline]
context_switch kernel/sched/core.c:5205 [inline]
__schedule+0xbaa/0xc90 kernel/sched/core.c:6867
preempt_schedule_common kernel/sched/core.c:7051 [inline]
__cond_resched+0x31/0x60 kernel/sched/core.c:7378
might_resched include/linux/kernel.h:61 [inline]
mutex_lock+0x22/0x90 kernel/locking/mutex.c:287
perf_poll+0x180/0x1f0 kernel/events/core.c:6150
vfs_poll include/linux/poll.h:82 [inline]
io_file_supports_nowait io_uring/rw.c:47 [inline]
__io_read+0x312/0xc50 io_uring/rw.c:936
io_read+0x4a/0x190 io_uring/rw.c:1030
__io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1793
io_issue_sqe+0x20b/0xc20 io_uring/io_uring.c:1816
io_queue_sqe io_uring/io_uring.c:2043 [inline]
io_req_task_submit+0x46/0xa0 io_uring/io_uring.c:1435
__io_run_local_work_loop io_uring/io_uring.c:1345 [inline]
__io_run_local_work+0x1f8/0x580 io_uring/io_uring.c:1370
io_run_local_work io_uring/io_uring.c:1411 [inline]
io_cqring_wait io_uring/io_uring.c:2718 [inline]
__do_sys_io_uring_enter io_uring/io_uring.c:3324 [inline]
__se_sys_io_uring_enter+0x159d/0x1c70 io_uring/io_uring.c:3224
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3224
x64_sys_call+0x27e4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:427
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888154b55288 of 8 bytes by task 5782 on cpu 0:
__perf_event_read_value+0xb6/0x1d0 kernel/events/core.c:5894
perf_read_one kernel/events/core.c:6049 [inline]
__perf_read kernel/events/core.c:6102 [inline]
perf_read+0x2d6/0x670 kernel/events/core.c:6119
loop_rw_iter+0x2c6/0x3f0 include/linux/uio.h:-1
io_iter_do_read io_uring/rw.c:836 [inline]
__io_read+0xbf6/0xc50 io_uring/rw.c:950
io_read+0x4a/0x190 io_uring/rw.c:1030
__io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1793
io_issue_sqe+0x20b/0xc20 io_uring/io_uring.c:1816
io_wq_submit_work+0x574/0x770 io_uring/io_uring.c:1928
io_worker_handle_work+0x41e/0x950 io_uring/io-wq.c:650
io_wq_worker+0x233/0x910 io_uring/io-wq.c:704
ret_from_fork+0x148/0x280 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x0000000015954eb2 -> 0x000000001595939d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5782 Comm: iou-wrk-5751 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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